package org.eclipse.jface.text;


/**
 * A document partitioner divides a document into a set of disjoint text
 * partitions. Each partition has a content type, an offset, and a length. The
 * document partitioner is connected to one document and informed about all
 * changes of this document before any of the document's document listeners. A
 * document partitioner can thus incrementally update on the receipt of a
 * document change event.
 * <p>
 * 
 * In order to provided backward compatibility for clients of
 * <code>IDocumentPartitioner</code>, extension interfaces are used to
 * provide a means of evolution. The following extension interfaces exist:
 * <ul>
 * <li> {@link org.eclipse.jface.text.IDocumentPartitionerExtension} since
 * version 2.0 replacing the <code>documentChanged</code> method with a new
 * one returning the minimal document region comprising all partition changes.</li>
 * <li> {@link org.eclipse.jface.text.IDocumentPartitionerExtension2} since
 * version 3.0 introducing zero-length partitions in conjunction with the
 * distinction between open and closed partitions. Also provides inside in the
 * implementation of the partitioner by exposing the position category used for
 * managing the partitioning information.</li>
 * <li> {@link org.eclipse.jface.text.IDocumentPartitionerExtension3} since
 * version 3.1 introducing rewrite session. It also replaces the existing
 * {@link #connect(IDocument)} method with a new one:
 * {@link org.eclipse.jface.text.IDocumentPartitionerExtension3#connect(IDocument, boolean)}.
 * </ul>
 * <p>
 * Clients may implement this interface and its extension interfaces or use the
 * standard implementation <code>DefaultPartitioner</code>.
 * </p>
 * 
 * @see org.eclipse.jface.text.IDocumentPartitionerExtension
 * @see org.eclipse.jface.text.IDocumentPartitionerExtension2
 * @see org.eclipse.jface.text.IDocument
 */
public interface IDocumentPartitioner {

	/**
	 * Connects the partitioner to a document. Connect indicates the begin of
	 * the usage of the receiver as partitioner of the given document. Thus,
	 * resources the partitioner needs to be operational for this document
	 * should be allocated.
	 * <p>
	 * 
	 * The caller of this method must ensure that this partitioner is also set
	 * as the document's document partitioner.
	 * <p>
	 * 
	 * This method has been replaced with
	 * {@link IDocumentPartitionerExtension3#connect(IDocument, boolean)}.
	 * Implementers should default a call <code>connect(document)</code> to
	 * <code>connect(document, false)</code> in order to sustain the same
	 * semantics.
	 * 
	 * @param document
	 *            the document to be connected to
	 */
	void connect(IDocument document);

	/**
	 * Disconnects the partitioner from the document it is connected to.
	 * Disconnect indicates the end of the usage of the receiver as partitioner
	 * of the connected document. Thus, resources the partitioner needed to be
	 * operation for its connected document should be deallocated.
	 * <p>
	 * The caller of this method should also must ensure that this partitioner
	 * is no longer the document's partitioner.
	 */
	void disconnect();

	/**
	 * Informs about a forthcoming document change. Will be called by the
	 * connected document and is not intended to be used by clients other than
	 * the connected document.
	 * 
	 * @param event
	 *            the event describing the forthcoming change
	 */
	void documentAboutToBeChanged(DocumentEvent event);

	/**
	 * The document has been changed. The partitioner updates the document's
	 * partitioning and returns whether the structure of the document
	 * partitioning has been changed, i.e. whether partitions have been added or
	 * removed. Will be called by the connected document and is not intended to
	 * be used by clients other than the connected document.
	 * <p>
	 * 
	 * This method has been replaced by
	 * {@link IDocumentPartitionerExtension#documentChanged2(DocumentEvent)}.
	 * 
	 * @param event
	 *            the event describing the document change
	 * @return <code>true</code> if partitioning changed
	 */
	boolean documentChanged(DocumentEvent event);

	/**
	 * Returns the set of all legal content types of this partitioner. I.e. any
	 * result delivered by this partitioner may not contain a content type which
	 * would not be included in this method's result.
	 * 
	 * @return the set of legal content types
	 */
	String[] getLegalContentTypes();

	/**
	 * Returns the content type of the partition containing the given offset in
	 * the connected document. There must be a document connected to this
	 * partitioner.
	 * <p>
	 * 
	 * Use {@link IDocumentPartitionerExtension2#getContentType(int, boolean)}
	 * when zero-length partitions are supported. In that case this method is
	 * equivalent:
	 * 
	 * <pre>
	 * IDocumentPartitionerExtension2 extension = (IDocumentPartitionerExtension2) partitioner;
	 * return extension.getContentType(offset, false);
	 * </pre>
	 * 
	 * @param offset
	 *            the offset in the connected document
	 * @return the content type of the offset's partition
	 */
	String getContentType(int offset);

	/**
	 * Returns the partitioning of the given range of the connected document.
	 * There must be a document connected to this partitioner.
	 * <p>
	 * 
	 * Use
	 * {@link IDocumentPartitionerExtension2#computePartitioning(int, int, boolean)}
	 * when zero-length partitions are supported. In that case this method is
	 * equivalent:
	 * 
	 * <pre>
	 * IDocumentPartitionerExtension2 extension = (IDocumentPartitionerExtension2) partitioner;
	 * return extension.computePartitioning(offset, length, false);
	 * </pre>
	 * 
	 * @param offset
	 *            the offset of the range of interest
	 * @param length
	 *            the length of the range of interest
	 * @return the partitioning of the range
	 */
	ITypedRegion[] computePartitioning(int offset, int length);

	/**
	 * Returns the partition containing the given offset of the connected
	 * document. There must be a document connected to this partitioner.
	 * <p>
	 * 
	 * Use {@link IDocumentPartitionerExtension2#getPartition(int, boolean)}
	 * when zero-length partitions are supported. In that case this method is
	 * equivalent:
	 * 
	 * <pre>
	 * IDocumentPartitionerExtension2 extension = (IDocumentPartitionerExtension2) partitioner;
	 * return extension.getPartition(offset, false);
	 * </pre>
	 * 
	 * @param offset
	 *            the offset for which to determine the partition
	 * @return the partition containing the offset
	 */
	ITypedRegion getPartition(int offset);
}